How can I successfully grow high-quality KDP crystals?

[Strange_matter]

TL;DR

I'm trying to grow a KDP crystal, but am having issues.

I've been trying to grow a KDP (potassium dihydrogen phosphate) crystal, but I'm having trouble growing anything. I've been adding potassium phosphate fertilizer to distilled water in a bottle I cleaned out and heating it to dissolve the chemicals, but so far haven't gotten much results. It's possible I'm not using enough chemicals. Oddly, one crystal did form at the bottom of the glass and nowhere else a few days ago, but when I moved the solution and dissolved more potassium phosphate the crystal dissolved again; possibly due to the solution still being hotter than I realized when I added the crystal. Can anyone explain the formation of the initial crystal? Could it be influenced by sound or vibration? Also tips on how to grow a crystal with decent quality would be appreciated.

 

[Borek]

First of all - check what the solubility at the experiment temperature is to make sure you have a saturated solution.

 

[Strange_matter]

First of all - check what the solubility at the experiment temperature is to make sure you have a saturated solution.

I may not be using enough fertilizer, so I can try adding more. I am still interested in how that initial crystal formed though. Do you have any idea? There was also something floating in the solution after the crystal formed, which may have been a small fragment of the ribbon I was using as a substrate to grow the crystal on. The crystal also seemed like it may have been growing in uneven, long pentagonal layers.

 

[Borek]

Seeding and growing crystals is a bit of black magic. In general they most likely form on some already existing solids (can be just a random dust particle). Growing nice ones is not easy either, sometimes (depends on the substance) requires a lot of patience (growing them fast rarely produces nice ones) and controlling of the conditions (especially the temperature must be held as stable as possible).

Fertilizer is definitely not pure, it is probably just "mostly" KDP, which may make your attempts a bit more difficult.